Calculating and measuring a researcher’s scientific impact is certainly not an easy task. Currently, one of the most common measures is the H-index, developed in 2005 by Professor Jorge Eduardo Hirsch to determine both the quantity and quality of an individual’s research performance/output. The index is a measure of the number of publications (productivity) a scientist has published and how often these papers are cited (impact). For example, if a scientist has an H-index of 15 this means that 15 papers have been cited at least 15 times.
The H-index of an author can be determined using Web of Science, Scopus, (MSK staff can access these two databases from the Library website) or Google Scholar; however it should be noted that the number may differ across sources due to their content scope — the depth and breadth of their collection policy. For this reason, it is important to always quote the source you used. And if you really want to, one can determine an author’s H-index manually by listing all their publications ranked in descending order by the number of citations these publications received. The value of H is equal to the number of papers (N) in the list that have N or more citations.
While the H-index can provide insight to a researcher’s contributions to the scientific community, does this number really provide the full picture or rather a limited view of research impact? It counts highly-cited papers regardless of why these papers are being referenced (e.g. for negative or poorly conducted research); it ignores the number and position of authors on the paper; it limits authors by the total number of publications so researchers just starting their career are at a disadvantage; it doesn’t take into account any major life events (e.g. women who have taken time off to start a family); and it doesn’t take into account other ways that researchers can effect change in their area of expertise or discipline.
There are also advantages to using the H-index. The focus is on the citation count to one’s papers and not the journal which is a better measure of a researcher’s contribution; it can be helpful for comparing researchers within a field at similar stages in their careers; and it may be used as a metric at a department or program level.
While no metric is perfect, the H-index is an interesting indicator that can be added to the bibliometrics toolkit in support of scholarly contributions. Perhaps it is only fitting to finish this post, keeping in mind the following quote from Albert Einstein – ”Not everything that can be counted counts, and not everything that counts can be counted.”
Donna Gibson
Director of Library Services